An analysis of diurnal variation in pain sensitivity in trigeminal areas-for establishing an effective drug treatment considering the administration time

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K11749
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Surgical dentistry
• Research Institution: Kagoshima University
• Principal Investigator: Sugimura Mitsutaka 鹿児島大学, 医歯学域歯学系, 教授 (90244954)
• Co-Investigator(Kenkyū-buntansha): 真鍋 庸三 鹿児島大学, 医歯学域附属病院, 講師 (90248550) ; 遠矢 明菜 鹿児島大学, 医歯学域附属病院, 助教 (80593649) ; 是枝 清孝 鹿児島大学, 医歯学域附属病院, 助教 (20760614) ; 山下 薫 鹿児島大学, 附属病院, 医員 (50762613) ; 大野 幸 鹿児島大学, 医歯学域附属病院, 助教 (00535693) ; 岐部 俊郎 鹿児島大学, 医歯学域歯学系, 助教 (50635480) ; 山形 和彰 鹿児島大学, 医歯学域附属病院, 助教 (40784195)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 痛覚 / 三叉神経系 / 概日リズム

Outline of Final Research Achievements

Since the 1990s, there has been a report on the diurnal variation of pain sensation with the progress in research on the internal clock. However, no report have been found about the trigeminal nervous system that controls the orofacial region responsible for delicate sensory functions. In this study, we examined the presence or absence of diurnal variation in pain-related behavior and in the expression nociceptive proteins in the trigeminal innervation region using an animal model of acute and persistent pain. As a result, the pain-related behavior observed by formalin injection was significantly longer in the dark period compared to the light period, and the number of c-Fos, the pain-related protein was significantly greater in the dark period than the light period. From the above, it was considered that there is circadian variation in nociception in the trigeminal region.

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Academic Significance and Societal Importance of the Research Achievements

本研究より、繊細な感覚機能が集中している三叉神経領域の痛みの感じ方には日内変動があることがわかった。今回得られた結果が、鎮痛薬などの投薬のタイミングを考慮した、より効果的で安全な薬物治療方法を確立することの一助となれば、その意義は極めて深いと考えられる。